Traditionally horses have been fed cereals as a good energy source. Oats are the cereal of choice for horses in hard work such as racehorses in training and many studs grow their own oats or have them grown locally by farmers. GAIN Equine Nutrition have the cereals grown for their feeds under licence by local farmers to guarantee quality.
Grains are the fruits of plants such as oats, barley, maize (corn) and wheat. Cereals are used in the production of compound horse feeds and are also sold as straights, but they are not natural feeds for horses. The digestive tract of the horse is naturally more suited to a forage diet. Cereals should always be fed with care, due to the high starch content. If overfed, glucose derived from starch digestion in the small intestine may overwhelm the small intestine’s capacity for absorption and pass into the hindgut where it may lead to dysbiosis (an imbalance of hindgut microbes).
Unprocessed cereal grains are not very digestible, so they must be processed to convert them into a nutritious feed. This is because the outer portion of the grain (the hull) is designed to protect the seed from harsh environments. The hull is so effective that if the seed is consumed unprocessed, it can pass through the entire digestive system with little or no digestion.
Oats have a higher fibre content than other cereals making them safer to feed as they are less likely to be overfed and problems related to dysbiosis such as laminitis and colic are less likely. Oat starch is also more digestible than other cereal starches. Oats are lower in digestible energy than maize and barley. Naked oats however are up to 30% higher as there is no fibrous husk and are higher in oil.
Oats may be lightly processed mechanically such as rolling, bruising or crushing although this does not increase the starch digestibility much, whereas cooking methods such as micronizing and extruding do.
Barley is a smaller grain with a harder outer covering than oats. It contains more digestible energy and less fibre than oats. Because the outer covering is hard, barley needs to be processed in order to break open the covering before it is fed to horses. Barley may be cooked, steamed, micronised or extruded; the purpose of all these processes is to make the starch more available and digestible to the horse.
Boiling barley used to be a common process in the winter months. Although this makes starch more digestible, this also destroys vitamins.
Maize also known as corn is higher in digestible energy than any other cereal grain. It is also low in fibre. It is more likely to be overfed and cause problems than oats or barley. Maize needs to be processed before feeding, usually by cracking, or micronising as the starch is difficult to digest in the small intestine.
Most wheat is used for human consumption i.e. the bread making, pastry and confectionery industry. Wheat (Triticum spp.) provides about 20% of food energy and protein around the world. 10% of the world wheat grain production is used for animal feed and wheat ranks third among cereals used for animal feeding.
Wheat byproducts used in horse feed include wheat bran, wheat shorts and middling and brewers’ grains.
Wheat has the same amount of digestible energy as maize and is also low in fibre. Wheat also contains a substance called gluten, which gives dough its elasticity. Wheat may form a dough ball type mess in the horse’s mouth particularly if ground wheat is fed. Wheat bran consists of the outer husk of wheat after the flour has been removed. This is a fibrous type material containing some protein with a poor (reverse) calcium to phosphorous ratio.
In fact, all the cereals contain low levels of calcium and high levels of phosphorus. This is an important factor to correct. The protein quality is also not great and in real terms cereals should be considered as simply a source of energy.
GAIN Equine Nutrition ensure that the natural deficiencies of cereals such as low calcium are corrected in the formulation of their compound feeds.
Cereals should therefore be fed with a specific oat balancer, a feed formulated to balance the nutrient deficiencies found in cereals.
The energy from starch is a fast release energy source as starch is readily broken down to sugar in the small intestine where it is rapidly absorbed into the horses’ bloodstream. The raise in blood sugar following a cereal “meal” causes the insulin level to rise. These fluctuations in insulin are thought to have an effect on growth hormone in young horses.
Processing Cereal Grains
Most grains should be processed before feeding. The purpose of mechanical processing is to break open the kernel so that once chewed and swallowed the digestive enzymes can access the starch for digestion. Mechanical processing does not improve digestibility much, whereas cooking methods of processing do break down the starch molecules a process known as “gelatinisation” to make the starch more digestible.
Micronising cereals consists of flaking and then heating in large machines similar to microwaves. The purpose of micronising is to break up the long starch chains so that the digestive enzymes can more easily break them down.
Extruding cereals involves cooking at high temperatures under great pressure, similar to popping corn (popcorn). Extrusion actually cooks the starch making it more digestible.
Cereal straights and feeds should be kept in a cool, dry environment once opened, to prolong their shelf life. Zoe Davies MSc.Eq.S.